著者

丸井 敦尚

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.123, no.2, pp.172-181, 2014-04-25 (Released:2014-05-16)

参考文献数

22

被引用文献数

2

---

The Kanto Plain is the biggest and deepest groundwater basin on the Japanese Islands. The water in the basin has been used in various purposes, and the volume of use is estimated to be the greatest in the country. Consequently, severe problems have emerged in the history of water development and water environment protection. The study show two stories in the groundwater basin of the Kanto Plain, corresponding to depth. The deeper one emphasizes salt water containing natural gas, and the shallow one is characterized by the largest groundwater flow system in the country. The paper reviews the geological features of the basin. Groundwater condition, especially deep groundwater, is also reviewed to understand the next stage of activities to develop and protect the environment.

著者

安原 正也 丸井 敦尚 布施谷 正人 石井 武政

出版者

公益社団法人 日本地理学会

雑誌

地理学評論 Ser. A

巻号頁・発行日

vol.64, no.10, pp.719-727, 1991

被引用文献数

6

---

The Tsukuba Upland, about 390 km² in area, is one of the diluvial uplands commonly found in the Kanto Plain (Fig. 1). The upland is composed of the Younger Kanto Loam (about 3m thick at most), the Joso Formation, and the Kioroshi Formation in descending order. In the upper part of the Joso Formation is a less-permeable clay/silt layer called the Joso Clay (Fig. 2). The present study aims at clarifying the physical properties of the Joso Clay, which are important from the hydrological point of view.<br> The Joso Clay was sampled at 19 points on the Tsukuba Upland for determination of its physical properties (_??_ in Fig. 1). The Younger Kanto Loam and the sands, situated above and below the Joso Clay, respectively, were also sampled for a comparison of physical properties. In addition, some data on physical properties of the Joso Clay were obtained from the literature (0 in Fig. 1).<br> Saturated hydraulic conductivities of the Joso Clay proved to be extremely low, ranging from 8.29&times;10^-6 to 5.30&times;10^-9cm/sec with an average value of 1.39&times;10^-6cm/sec (Table 1). The Joso Clay presented a remarkable contrast in saturated hydraulic conductivity to both the overlying Younger Kanto Loam and the underlying sands, showing differences of two to three and three to five orders of magnitude, respectively (Fig. 3).<br> The porosity of the Joso Clay was between 54% and 77%. The Joso Clay showed a high degree of variability in thickness, from 15 to 400cm (Fig. 4). No macropores or non-capillary pores with the pore diameters larger than 3.8&times;10^-2mm were found in the Joso Clay (Fig. 5), indicating that almost all the water in the Joso Clay moves very sluggishly.<br> Based on the results of this study, vertical subsurface water movement in surface parts of the Tsukuba Upland is assumed to be substantially restricted due to the presence of the Joso Clay.

著者

高村 弘毅 丸井 敦尚

出版者

日本海水学会

雑誌

日本海水学会誌 (ISSN:03694550)

巻号頁・発行日

vol.60, no.2, pp.86-90, 2006 (Released:2013-02-19)

参考文献数

16

---

Groundwater is well known as a natural resource that includes dissolved solution according to the geology, origin, flow route and storage condition. The calling code of the deep groundwater is divided by the saline concentration and condition, in usual. Brine, saline, brackish are the technical words of groundwater depended by the salinity, on the other hand, fresh and fossil are the words of groundwater condition. The study is introducing the previous studies and makes a scientific define of the Brine Water in the field of groundwater hydrology. The study also shows the sample of brine water in the Kanto basin, which is the largest and deepest deposit basin in Japan.

著者

越谷 賢 丸井 敦尚

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.121, no.3, pp.421-440, 2012-06-25 (Released:2012-07-09)

参考文献数

38

---

Three-dimensional earth sciences information is being made available in digital formats because such information is useful and understandable to various users. In this study, we develop a three-dimensional hydrogeological model of Tsukuba City and the surrounding region, and develop a method for estimating the hydraulic conductivity of aquifers in combination with the three-dimensional hydrogeological model and other related hydrogeological information with the primary objective of proposing a method for evaluating groundwater resources. The three-dimensional hydrogeological model was developed using a geological map and drilling data with data interpolated using a geostatistical method. The model developed reproduced the data used well, and it was found to be accurate for practical use. Moreover, this model could be used for various types of visualization, from which information could be extracted and applied immediately to numerical simulations; this provided information that was useful and understandable for evaluating groundwater resources. The proposed method for estimating the hydraulic conductivity of aquifers was developed from hydraulic conductivities obtained from various drilling surveys, which were grouped together taking geology and stratigraphy into consideration based on a three-dimensional hydrogeological model, and using a statistical analysis. This method can be used to rapidly evaluate trends in hydraulic conductivity by integrating data distributed over a broad area. In addition, if a columnar section of an evaluated point is obtained, this method can be used to determine the actual hydraulic conductivity of aquifers. Therefore, these methods were found to be effective for evaluating groundwater resources.